130 FLORIDA GEOLOGICAL SURVEY-I3TH ANNUAL REPORT

 8. PENINSULAR FLATWOODS, WESTERN DIVISION
 (Figs. 23-25. Soil analyses 27-36, I, J, X.)
 Besides the flatwoods already described, there is a much larger area, covering the greater part of the peninsula south of our limits, Which may be divided into several regions when it is more thoroughly explored. In the latitudes under consideration it is divided by the lake region into two parts, which may conveniently be treated separately. The western portion, which will be discussed first, has an area of about 1,700 square miles.
 Geology. The strata beneath the surface sands range from Upper Oligocene to Pliocene, and are more or less calcareous and phosphatic; and although natural exposures are compara-tively rare, they influence the soil perceptibly in many places. The Pliocene is represented by the Bone Valley formation, which includes the pebble phosphate deposits, and is chiefly confined to Polk County. The mining of this phosphate is perhaps the most important industry in the region. Flowing artesian wells can be had almost anywhere o near the coast. There are a few mineral springs, such as Espiritu
 Santo near Safety Harbor and Kissingen near Bartow.
 Topography. The surface is comparatively level, as implied by the name "flatwoods," but fairly "well drained." It has the appearance of having been uplifted a little in comparatively recent times, for near the coast and rivers one can in many places ascend 25 feet in less than a mile, and numerous creeks and branches have cut narrow valleys below the general level. San Antonio, at the upper edge of the region in Pasco County, is said to be, 160 feet above sea-level. Shallow depressions a few acres in extent, which hold a foot or two of water in wet seasons, are very common, especially northward, but there are very few lakes, the ponds being in most cases well filled with cypress and other trees. There, are more streams in proportion to area than in the other regions, but none of them are considered navigable.
 Soils. The soil is nearly everywhere sand, of various colors
 from white to brown, but the underlying rock or marl seems to be usually within a few feet of the surface, making calcareous soils in many low places. The'soil surveys of Pinellas and Hillsborough Counties (1914 and 1918) cover the greater part of the area. In those publications the soils are referred to the "Leon," "Ports-